So can we assume that the problem was resolved? The shut off diaphragm on the 603 motor isn't the easiest to get at. If the guy can do it in 1.2 hours, it's one of the benefits of practice. You get quicker, not slower. The first one I did on a 300SDL in 1990 took a good me hour to figure out that the intake was supposed to come off...but I learned.
Regards,
Randy D.